Arc rupturing device for electric safety fuses



E. LANGE March 23, 1937.

Filed Dec. 10, 1935 Patented Mar. 23, 1937 PATENT OFFICE ARC RUPTURING DEVICE FOR ELECTRIC SAFETY FUSES Emil Lange, Berlin-Zehlendorf, Germany Application December 10, 1935, Serial No. 53,750 In Germany January 14, 1935 3 Claims.

This invention relates to an electric safety fuse for high tension currents of the kind wherein the are formed between the contacts on fusing of the wires, is ruptured by a blast produced by the arc itself as it heats the fluid content of the fuse casing. I

The object of the invention is to provide means for maintaining the blast itself as cool as possible in order to ensure a reliable rupturing of the arc, and the invention consists essentially in the provision of means for forming one are at the outlet of the casing and another are within a confined space in the casing communicating with the outlet through a circuitous route, so

that the pressure produced by the heating of the fluid in said space will cause the comparatively cold fluid in the principal space of the casing to be ejected through the outlet and to rupture the are at the latter.

Figs. 1 and 2 of the accompanying drawing represent longitudinal sections of different forms of fuses constructed according to the invention.

In each instance the safety fuse comprises a casing I of insulating material fltted at the ends with closing members 8 and 9 forming contacts for connecting the fuse to a high tension electric circuit A plug 3 in the casing forms a narrow outlet for the air or other fluid obtained in the casing. Supported in a central position within the casing by means of a spider I0, is a bell 5 the crown of which is'turned towards the outlet of the casing. The bell is made of insulating material and carries at the crown a conducting member 6 which is connected by fuse wires to the contacts 8 and 8. One wire I passes through the bell 5 and is connected to a lug 2 on the contact 9. In the arrangement shown in Fig.1, the second fuse wire 4' is connected to the plug 3 within the outlet opening.

On the fusing of the wires one arc will be formed in the outlet between the conducting member 6 and the plug 3. Another arc will be formed inside the bell 5 between the conducting member and the lug 2. The air or other fluid contained within the bell will thus be strongly heated, and the ensuing pressure will be communicated to the space outside the bell which still contains comparatively cold fluid. This fluid or part thereof will be ejected through the outlet, and the arc will be ruptured in the latter.

The outlet may be closed by a spring-controlled valve 1 adapted to open at a given pres- 5 sure in order to produce a strong blast.

In the arrangement shown in Fig. 2 a fuse wire 4 is run through the outlet from the conducting member 6 to the closing valve H and connected to the latter. 10

I claim:

1. An electric safety fuse of the character described comprising an insulating casing containing fluid and having at one end thereof a narrow outlet for said fluid, a contact member at 15 each end of the casing, a confined space in said casing communicating with the outlet through a circuitous route, and fuse wires connecting the contacts through the outlet and through said space so that, on a fusing of the wires, area 20 will be formed at the outlet as well as in said space and so that the heating of the fluid in the latter will cause the fluid outside the space to be ejected through the outlet for,rupturing the arc.

2. An electric safety fuse of the character described comprising an insulating casing containing a fluid and having at one end a narrow outlet for said fluid, a contact member at each end of the casing, a bell of insulating material 30 supported within the casing with the crown turned towards the outlet, a conducting member fitted in the crown of the bell, and fuse wires connecting said conducting member with one contact through the outlet and with the other 35 contact through the bell so that, on fusing of the wires, arcs will be formed at the outlet as well as within the bell, the latter being arranged so that the fluid pressure within it caused by the arc will causethe fluid outside it to be ejected through the outlet for rupturing the are at the latter 3. The electric fuse claimed in claim 2 in combination with a spring-controlled valve normally closing the outlet and adapted to open at a 45 given pressure of the fluid.

Eli/LE LANGE'. 

